Creating Instances

Once you have defined a class, you can create new instances of that
class by calling its create() method. Any methods, properties and
computed properties you defined on the class will be available to
instances:

For performance reasons, note that you cannot redefine an instance's
computed properties or methods when calling create(), nor can you
define new ones. You should only set simple properties when calling
create(). If you need to define or redefine methods or computed
properties, create a new subclass and instantiate that.

By convention, properties or variables that hold classes are
PascalCased, while instances are not. So, for example, the variable
App.Person would point to a class, while person would point to an instance
(usually of the App.Person class). You should stick to these naming
conventions in your Ember applications.

Initializing Instances

When a new instance is created, its init method is invoked
automatically. This is the ideal place to do setup required on new
instances:

If you are subclassing a framework class, like Ember.View or
Ember.ArrayController, and you override the init method, make sure
you call this._super()! If you don't, the system may not have an
opportunity to do important setup work, and you'll see strange behavior
in your application.

When accessing the properties of an object, use the get
and set accessor methods: